Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Content-Type: text/plain;
        charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3731.500.231\))
Subject: Re: [PATCH] bcache: make kobj_type structures constant
From:   Coly Li <colyli@suse.de>
In-Reply-To: <4cc38847-a967-487b-8efe-81b741ab6782@t-8ch.de>
Date:   Wed, 5 Apr 2023 21:38:01 +0800
Cc:     Kent Overstreet <kent.overstreet@gmail.com>,
        linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <F63C6A45-E428-4557-9995-FDB43CE243B3@suse.de>
References: <20230214-kobj_type-bcache-v1-1-cf00ead7bee7@weissschuh.net>
 <125CA8D6-D3B7-42FB-83BE-DCA688F2ACAF@suse.de>
 <20230214152119.epkfhkojqjvokqmv@t-8ch.de>
 <9DE71214-283C-4410-B5A4-22DFDA7021F4@suse.de>
 <4cc38847-a967-487b-8efe-81b741ab6782@t-8ch.de>
To:     =?utf-8?Q?Thomas_Wei=C3=9Fschuh?= <linux@weissschuh.net>
Precedence: bulk


> 2023=E5=B9=B44=E6=9C=885=E6=97=A5 01:38=EF=BC=8CThomas Wei=C3=9Fschuh =
<linux@weissschuh.net> =E5=86=99=E9=81=93=EF=BC=9A
>=20
> Hi Coly,
>=20
> On 2023-02-15 00:16:03+0800, Coly Li wrote:
>>> 2023=E5=B9=B42=E6=9C=8814=E6=97=A5 23:21=EF=BC=8CThomas Wei=C3=9Fschuh=
 <linux@weissschuh.net> =E5=86=99=E9=81=93=EF=BC=9A
>>>=20
>>> On Tue, Feb 14, 2023 at 05:51:09PM +0800, Coly Li wrote:
>>>>=20
>>>>=20
>>>>> 2023=E5=B9=B42=E6=9C=8814=E6=97=A5 11:13=EF=BC=8CThomas Wei=C3=9Fsch=
uh <linux@weissschuh.net> =E5=86=99=E9=81=93=EF=BC=9A
>>>>>=20
>>>>> Since commit ee6d3dd4ed48 ("driver core: make kobj_type =
constant.")
>>>>> the driver core allows the usage of const struct kobj_type.
>>>>>=20
>>>>> Take advantage of this to constify the structure definitions to =
prevent
>>>>> modification at runtime.
>>>>>=20
>>>>=20
>>>> How the const structure definition can prevent modification at run =
time?
>>>=20
>>> It will be put into .rodata instead of .data by the compiler.
>>> The .rodata section is mapped as read-only via the pagetable.
>>>=20
>>> See Documentation/security/self-protection.rst
>>> "Function pointers and sensitive variables must not be writable".
>>=20
>> I see. Thanks for the information.
>>=20
>> This patch will be added into my testing queue, and submitted later.
>=20
> It seems this was not submitted.
> Or did I miss it?

No I don=E2=80=99t submit it yet. It is not emergent fix, and stay with =
other testing patches together.

Do you want it to go now?

Coly Li